The use of hydroxyl radicals as an airborne disinfectant in hospitals and other indoor environments is now becoming widespread. The disinfectant property of hydroxyl radicals has been known since the publication of research conducted in the 1960s at Porton Down in the UK and TNO in The Netherlands. Air based disinfection using hydroxyl radicals mimics a naturally occurring process in the outdoor environment, and so the concentration of hydroxyl radicals in the air is sometimes referred to as the “open air factor”.
One example of an apparatus for generating hydroxyl radicals for airborne disinfectant is described in WO 2005/026044. A further apparatus is described in WO 2008/125879. The essential components of the apparatuses described in these documents are a supply of olefin, such as terpene, and a supply of ozone. An olefin vapour is produced from the supply of olefin and is mixed and reacts with the ozone to produce hydroxyl radicals.
While this basic chemistry for producing hydroxyl radicals is now well understood, there is a need to provide a convenient, safe and effective system for supplying hydroxyl radicals to an indoor environment. In particular, it would be desirable to provide a system that can be continuously and effectively operated by consumers with minimal interruption for maintenance and replenishment.